Internal combustion engine



' Jan. 5, 1937. I H. c; EDWARDS ,0

INTERNAL COMBUS T ION ENGINE Filed Dec. 28, 1931 2 Sheets-Sheet l 4e 53 4/ Z w, .40 y I :2 3 I I a7 .62 1911- r v /3 1 l I4 5 x22 W /fi dbbowu/ fir-7 MfiZMpM Jan. 5, 1937. H. c. EDWARDS INTERNAL COMBUSTION ENGINE Filed Dec. 28, 1951 2 Sheets-Sheet 2 gwuemtoz M ZZM Patented Jan. 5, 1937 UNITED STATES PATENT OFFICE INTERNAL COMBUSTION ENGINE Application December 28, 1931, Serial No. 583,455

5 Claims.

This invention relates to internal combustion engines and more particularly to internal combustion engine cylinders of the air-cooled poppet valve type. It is the primary object of the invention to provide a cylinder characterized by light weight and adequate strength which is inexpensive to manufacture.

Cylinders either of steel or aluminum for use in air cooled' internal combustion engines are ordinarily provided with a separate aluminum cooling head, the cylinder and cooling head being provided with fins to increase the rate of heat transfer. This construction is found, however, disadvantageous in several respects. For instance, since the explosive mixture is confined to the outer portion of the cylinder when ignition occurs, this portion acquires the highest temperature and dilficulty is experienced in conducting this excessive heat from the cylinder to the cooling head regardless of the intimate nature of the contact between the engaging surfaces of the cooling head and the cylinder. Since the valves and the valve operating mechanism are ordinarily mounted on the cylinder head, it is essential that the lowest possible temperature be maintained at this point. Furthermorait is impossible to provide very thin cooling fins of aluminum and at the same time to ensure adequate mechanical strength of the fins.

The present invention, therefore, contemplates the provision of an integral cylinder body and head of forged steel, cooling .fins being provided on both the body of the cylinder and the head whereby the provision of an additional cooling head may be eliminated. It is found in practice that the additional strength of the steel permits reduction of the thickness of the cylinder walls and head and reduction of the thickness of the cooling fins to such an extent that for a given minimum strength of the parts, the weight of the cylinder can actually be reduced. Furthermore, the reduction in the thickness of the fins permits a material increase in the number of fins per unit area so that more efficient cooling is obtained. It is found, for instance, that steel cooling :fins of approximately one fourth the thickness of aluminum fins will afford the same mechanical strength and approximately the same rate of heat transfer. 7

A more specific object of the invention is the provision of a one-piece cylinder having fiat surfaces formed exteriorly of the head thereof, these surfaces being inclined with respect to the axis of the cylinder, and valve housings secured to the cylinder head and seating on these fiat surfaces. The construction is preferably such that separate housings are provided for the inlet and exhaust valves, these housings being sufficiently small to permit the cutting of cooling fins over the major portion of the cylinder head to ensure adequate cooling thereof.

It is a further feature of the invention to provide a baffle for directing air downwardly on the cylinder head at the rear thereof or on that portion of the cylinder which is more remote as regards the normal direction of movement of air past the cylinder. This baffle is preferably positioned over the cylinder head and may be carried by or formed integrally with the valve housmgs.

Further objects and features of the invention will be apparent from the following description, taken in connection with the accompanying drawings, in which Figure 1 is a longitudinal sectional view of a cylinder constructed in accordance with the principles of the invention, this section being taken on substantially the line I-l of Figure 2;

Figure 2 is a plan view of the cylinder shown in Figure 1 with the valve housings removed;

Figure 3 is a rear elevation of the upper portion of this cylinder and head;

Figure 4 is a section on the line 4---4 of Figure 1; and

Figure 5 is a section on the line 5-5 of Figure 1.

In order to facilitate an understanding of the invention, a specific embodiment of the principles of the invention is illustrated in the drawings, this embodiment being described in detail in the specification. It will nevertheless be understood that various changes and alterations in the arrangement thus shown and described are contemplated and that there is no intention of limiting the invention in accordance with the specific language used herein.

Referring to the drawings, it will be observed that the cylinder, indicated by the reference numeral I0, is "constructed as a separate unit and is designed to seat Within an aperture in the crankcase (not shown), it being understood that a plurality of cylinders are ordinarily employed in a single engine. The manner in which the cylinder is assembled in the crankcase and retained in position thereon forms no part of the present invention.

The cylinder essentially comprises two parts, a cylindrical body portion H and a head portion 13 formedfintegrally with the body portion. As explained hereinbefore, the cylinder is of forged steel, and the body portion is provided with a plurality of thin fins [5 formed by cutting a series of annular grooves in the outer wall thereof. By reason of the fact that the material employed is forged steel, a very large number of extremely thin fins can be provided in this way without sacrificing the mechanical strength of the fins, and the cylinder walls may have a minimum thickness dependent upon the pressure to which they are subjected. By reason of the excellent wearing properties of steel, the provision of a separate liner commonly used in connection with aluminum cylinders is unnecessary, and thus the difiiculties resulting from unequal expansion of the cylinder and liner and the consequent reduction of the rate of heat transfer from the inside to the outside of the cylinder are avoided.

The outer surface of the cylinder head 13 is provided with two flattened portions I6 and I8 arranged to receive valve housing means hereinafter described. These flattened portions arepreferably defined by planes intersecting in a line extending transversely of the cylinder and passing adjacent the cylinder axis, the planes forming acute angles with the axis of the cylinder and obtuse angles with the elements of the cylinder walls, so that the outer surface of the cylinder head is peaked as indicated in Figures 1 and 3.

The cylinder head is further formed with an exhaust port 22, an inlet port 24, and a threaded opening 25 arranged to receive a spark plug or other ignition means. A series of parallel transverse cuts are made in the cylinder head to provide fins 2'1 extending over the entire surface thereof with the exception of portions of this surface immediately adjacent the ports 22 and 24 on which the valve housing means is adapted to seat. H

It will be noted that the provision of parallel fins on the cylinder headisa marked improvement over arrangements employing circularly arranged fins since the straight parallel fins may be positioned to extend in the direction of movement of air past the cylinder and the machining of the fins is faciltated to a considerable extent with the result that fins of less thickness and greater number can be provided.

It is important to note that, by reasonof the fact that the valve housing meansis not subjected to the higher cylinder pressures, these pressures being exerted against the head l3 which is integral with the body portion ll of thecylinder, it is not necessary to have any finished surfaces on the cylinder. It is thus sufficient to form the flattened portions of the outer surface of the cylinder head by a milling operation since any leakage between the valve housing means and the cylinder head will result only from the relatively small pressure differences existing in the inlet port and exhaust port at the time of opening of the corresponding valves.

It is also a feature of the invention to first form the head with the fins and to thereafter mill the finned head to form the seat for the valve housing means, the angular formation of the cylinder head permitting the fabrication of the cylinder in this manner.

The valve housing means preferably comprises separate members, an exhaust valve housing or compartment 30 and an intake valve compartment 32. The exhaust valve, comprising a head 33 and a stem 34, is supported by means of a bushing 36 for sliding movement in a guide 31 preferably formed integrally with the housing-30, the valve head engaging a seat 39 surrounding the exhaust port 22. The inlet valve, consisting of the head 40 and the stem 4|, is similarly supported by means of a bushing 43 for sliding movement in a guide 45 and is arranged to engage a seat 46 surrounding the inlet port. Exhaust and inlet conduits, numbered 48 and 50, are associated respectively with the cylinder ports 22 and 24.

The cylinder head is provided with threaded recesses 52 adapted to receive bolts 53 passing through bosses 54 formed on the two valve compartments for securing these compartments in position on the cylinder head and in contact with the flattened portions thereof. A threaded recess 5B is provided in the cylinder head intermediate the valve compartments for receiving the bolt 51 provided with a head 58 and a washer 59, the latter engaging the adjacent portions of both valve compartments.

' A baffle comprising two portions 60 and GI is positioned over the cylinder head and between the valve compartments 30 and 32. The portion 60 of the baffle is preferably formed integrally with the valve compartment 30, and the portion 6| is similarly formed on the valve compartment 32, these portions substantially abutting adjacent the central axis of the cylinder. The bafile is constructed, as shown in dotted lines in Figure 4 of the drawings, to extend downwardly toward the rear of the cylinder, it being understood that the rear of the cylinder is that portion remote as regards the direction of the flow of air past the cylinder. Thus, air striking the baflle will be deflected downwardly on the cylinder head and the rear portion of the body of the cylinder to ensure adequate cooling thereof, the rear portion of the cylinder ordinarily being shieldedto some extent from the cool air.

Each of the valve housings or compartments 30 and 32 is formed with openings in the upper portions thereof to provide access to the valve parts for replacement and repair, these openings being normally closed by spring covers 10. The valve actuating means may be of any conventional type, the valve being urged to seating,

position by coiled springs 12 acting between the" valve compartments and the head members 13 threaded on the upper end of the valve stems. Rocker arms 15 pivoted at 16 in each valve compartment engage the ends of the respective valve stems and are actuated by rods 18 in any wellknown manner.

It will be appreciated that the cylinder and valve housing construction disclosed herein may be easily and cheaply constructed and assembled -5 and that adequate and substantially uniform cooling thereof is assured.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In an internal combustion engine, the combmation with a forged steel cylinder having an integrally formed head, the exterior of said head having flattened portions defined by planes forming acute angles with the axis of the cylinder, of valve housing means secured to the head and seated on said flattened portions, and a baffle associated with said cylinder and positioned above the head for directing a current of air downwardly on that portion of the cylinder remoteand a head portion, both of said portions being provided with cooling fins, of a baflle supported on the head portion of the cylinder and positioned above the same for directing a current of air downwardly on that portion of the cylinder remote as regards the normal direction of movement of air past the cylinder.

3. In an internal combustion engine, the combination with a cylinder having a body portion and a head portion, both of said portions being provided with cooling fins, of valve housing means secured to said head, and a baffle carried by said means for directing a current of air downwardly on that portion of the cylinder remote as regards the normal direction of movement of air past the cylinder.

4. In an internal combustion engine, the combination with a cylinder having a body portion and a head portion, both of said portions being provided with cooling fins, of valve housing means secured to said head, and a bafile formed integrally with said means for directing a current of air downwardly on that portion of the cylinder remote as regards the normal direction of movement of air past the cylinder.

5. In an internal combustion engine, the combination with a cylinder having a body portion and a head portion, both of said portions being provided with cooling fins, of valve housings for exhaust and inlet valves secured to said head, and baffle means carried by and extending between said housings for directing a current of air downwardly on that portion of the cylinder remote as regards the normal direction of movement of air past the cylinder.

HERBERT C. EDWARDS. 

